Experimental Study of Quenching Progression on a Heated Flat Dimpled Surface with Water Jet Impingement

Quenching progression on a flat surface and heat transfer enhancement with an impinging jet over smooth and dimpled surface modification is presented in this manuscript. With rapid advancements in today’s electronic, electrical, and mechanical systems, the need for the removal of the associated heat generation rates is also increasing. Achieving that by jet impingement provides an economical and fast solution. A smooth flat plate is quenched repeatedly from three different initial temperatures of ۳۰۰,۳۵۰ and ۴۰۰° C. The results in terms of re-wetting parameters viz., Re-wetting temperature, and wetting delay are reported. Parallelly, the effect of the hemispherical dimpled (array) surface with a pitch of ۳ mm, and diameter of ۲ mm with varying depths of ۰.۵ mm(d/t=۱۰) and ۱mm(d/t=۵) are studied. The results are then compared to that of a smooth surface. Water is used as a coolant at a temperature of ۱۷ ±۲°C. A large deviation in results is reported when the plate surface was subjected to repeated trials due to a change in the metallurgical properties of the surface. The results of a dimple depth of ۰.۵mm show a higher heat transfer rate as compared to that of both the smooth surface and the dimple depth of ۱ mm. A maximum of ۴۰% and a minimum of ۲۶% enhancement in heat transfer rate is reported for dimple depth ۰.۵mm compared to ۱mm. Further, a ۵۹.۷۶% of heat transfer efficiency was recorded for the experimental setup and this efficiency was found to be increasing with an increase in the water pump pressure.

Keywords:

Jet Impingement , Rewetting Temperature , Flow boiling , Heat transfer augmentation , Wetting front